This guide describes parking garage lighting requirements and explains layout requirements for specific parking garage fixtures.
Table-1 shows luminance criteria for areas of the garage.
Table 1
Bold text & highlight shows areas that can be achieved with properly designed LED luminaires. Note the orange/red highlight is a problem area for general "downlight" fixtures. A downlight fixture cannot provide the Level A vertical footcandles without creating glare in Level B and Level C, which also wastes light and energy. Typical down lights also cannot provide up-light which is desired for parking garage lighting. Up-light is not required in either parking garage Standard, however, Vertical footcandles are specified. A properly designed LED parking garage light will provide illumination for vertical walls with less waste and glare in other areas, and up-light improves ambiance. These luminaires may be used for garages, tunnels or installations having a ceiling or vertical surface that requires illumination above the floor. Luminaires with up-light should not be used outdoors if night sky light pollution is to be avoided. 
Cutoff is essential on the motorist approach side to prevent blinding the driver.
The luminaire should be available with cutoff specified, or it should be field adjustable.
The required cutoff angle will depend on the application and mounting height. | ||||||||||||||||||||||||||||||||
A common configuration for parking garage mounting heights of 8 feet will be 24° on the driver approach and 60° on the downstream side.
Reflectance adds to the room illumination, and is a function of surface condition. White light against a smooth gray surface will reflect approximately 50%. A whiter light may find more reflective surfaces than a lower color temperature or monochromatic light source (Sodium Light). In commercial settings with white light, wall reflectance is often estimated at 50%, ceilings 80% and floors 20%, or, that's the amount we use in calculations.
Smooth gray concrete walls can naturally have a 50% reflectance value. White paint on ceilings will easily boost those to 80% reflectance. Ceilings should always be painted if possible. Floor reflectance is typically low, and using that in calculations is misleading because a full garage will have most of the floor covered with vehicles. Its light enhancing benefit will change with garage activity and maintenance. Walls and ceilings usually contribute to better lighting as they enhance and smooth the total room illumination.
Clean, reflective surfaces can improve the overall Average to Minimum Illumination Ratio, and when surface treatment and painting is designed in from the project start, more energy can be saved. Using the dimensions of the following layout examples for a 120' x 80' garage, proper painting of the walls can boost reflectance by over 20%, and could allow reduction by that much in energy usage with no reduction in illumination quality.
Conceptually we may consider a Parking Module as six parking stalls within an area approximately 28' x 60' as illustrated here. This helps us define the lighting requirements.
There are multiples of these modules, end to end, or side to side. Typical overhead beam spacing is about 18 to 22 ft. centers where luminaires can mount on, or in between. But parking modules don't always fit according to the beams. Here are two basic layouts: The first illustrates Structure Across a parking module. The second illustrates Structure Aligned with a parking module. The structure often has only eight feet of clearance, and the larger luminaires must fit between beams. Where Luminaires must fit between beams, the lighted path must follow the beams, and lighting is limited to a stripe fashion. Lighting manufacturers have provided for two commonly known lighting layouts: "single row" and "double row" designs. Of course variations arise because every floor plan has its unique drive aisles and turns, signage locations, corners, windows and stall walls. | 
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Single row lighting is illustrated to the right for an enclosed floor plan. Luminaires are centered above each drive aisle to light the length of parking modules. Each luminaire is set to cutoff (the curved-in shape) to the drive aisle direction to reduce the disability glare toward the driver.
This floor plan requires eight luminaires to adequately light the area to standards.
Note that one location has a luminaire facing directly into the drive aisle. A Hybrid is used here to reduce glare toward the driver, while also providing uplight. The opposite wing fully illuminates the far corner walls of the parking module. This is one example of combining photometrics in one luminaire. The Luminaire could provide a streetlight-type output with uplight in one wing, and a standard parking garage output in the other wing. If the North or South sides had windows or were open, the luminaire can be ordered with side cutoff down to 24° to limit trespass. Also note that in this layout, if the center wall was not separating the inside border of parking modules, motorists entering the inside parking stalls would face directly into bright light from the opposite modules. In this case, the designer can specify the Hybrid cutoff model for an optimum solution. Double row lighting is illustrated to the right, with a row of luminaires aligned along each side of each drive aisle. These luminaires are ordinarily the same as for single row, but rotated 90° and overlapped lengthwise according to structure spacing. Side cutoff can be adjusted down to 24° to reduce wall illumination and possibly allow open walls or windows on these East and West sidewalls. The floor plan shown will have vertical illumination at the North and South sides when using the luminaire. If there are windows or no walls at North or South sides, the Hybrid is a better choice with its specific above-floor cutoff characteristic. |
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Photometric Viewer Downloads: Simkar Indoor Lighting Layout Software Acuity Photometric Viewer 3.3
Look for RP20 at IESNA and look to National Parking Association for Standards The lighting system design must account for each interior surface having either light reflectivity or light absorption. When a surface isn't present, that border must be considered an opening through which light will escape. Open areas or windows require cutoff luminaires to avoid waste and avoid sending light pollution elsewhere. Given the vertical illumination that standards suggest, light energy can go right out the window. Outward-facing luminaires must have sharp downward cutoff, or, they must be wall mounted and shine back into the area. Windows or open back-to-back parking bays require more attention to layout.
Painting of interior surfaces is not essential, however, this Program is about conserving energy. Some manufacturer's paint and surface treatments not only boost reflectance, they repel typical garage dirt and hydrocarbon buildup to maintain that reflectance over long periods of time.
The low profile allows LED luminaires to mount either on the beams or suspend between the beams, when HID and Induction luminaires are too bulky.